Method of forming a butterfly valve

ABSTRACT

A butterfly valve in which the seat is formed of a stainless steel ring fused to the valve body by casting the body about the prepositioned ring prior to the finished machining thereof.

United States Patent Inventors Appl. No. Filed Patented Assignee Donald L. Geiselman;

Frederick T. Newell, both of Bradford, Pa. 862,577

Aug. 18, 1969 July 20, I971 Dresser Industries, Inc.,

Dallas, Tex.

Continuation-impart of application Ser. No. 604,090, Oct. 31, 1966, now Patent No. 3,420,500, Original application Apr. 17, 1967, Ser. No. 631,255, now Patent No. 3,525,499.

METHOD OF FORMING A BUTTERFLY VALVE 6 Claims, 9 Drawing Figs.

US. Cl 29/l57.1 R, 29/156.7 A, 29/527.6, 29/DIG. 8, 164/99 nn. Cl. ..B23p 15/26. 323p 17/00, 323k 19/00 Field oISearch 251/306;

29/157.1R, 156.7 A, DIG. 5, DIG. 8, 527.6; 164/95, 98, 99

Primary Examiner-John F. Campbell Assistant Examiner-D. C. Reiley Attorneys- Robert W. Meyer, Daniel Rubin, Peter .1. Murphy,

Roy L. Van Winkle and William E. Johnson, Jr.

ABSTRACT: A butterfly valve in which the seat is formed of a stainless steel ring fused to the valve body by casting the body about the prepositioned ring prior to the finished machining thereof.

The prior art to which the-invention is directed: includes. the

art of butterfly valves being of atypein which a usually circular vane or disc is rotatable in the valve passage between an open. and closed position. When in the closed position, the: vaneengages a seat with which itcooperates to provide. aseal against leakage of the pressurizedline'contents intended to be controlled by the valve. It is essentialin valves of thistype that the seal beaeffective-on each occasion of valve closing-for the.

life of the valve to continuously provide positive shutoff without frequent maintenance and servicing of the seat. Because the seat is commonly subjected'to wearing conditions caused by factors such as wire-drawing, corrosion, temperature changes, abrasions and the like, it is desirable to providean ideal seat which is completely unaffected'bythesefactors. Accordingly, it has longbeen recognized that the seat should. comprise a hard, durable corrosion-resistant'material able to at least substantially retain-its machine-finished surface to withstand normal and conventional conditions-:and: providetrouble-free servicev for very. prolonged. operating periods. Previous efforts to achievethis result haveincludedthe use of premachined alloyed materials for-xth'e seat placed into the valve body as a production step'subsequent to thecastingof the valve body by cementing or the: like. This .hasachieved only a limitedsuccess fora short time following manufacture because ofjthe inability of the cement to maintain its bond for the life. of the valve; Leakage occurs as the bond, affected by the conditions of use, begins-to fail,.frequently-aft'er only a:

short timeperiod of operative-service. At thesame-time, it had not been known to fuse a suitableseat material into thevalve' body during casting of the latter-sincethe differenceiniexpam sion-coefficients between the b'odyandi seat materials has heretofore caused the ringto separate-fromthe -valvebody occasioned by the difference in shrinkage duringthe cooldown' after-casting;

SUMMARY OF THEINVENTION' This invention relates to valves and'. to the process .of their manufacture. More particularly, the invention relates to' butterfly-valves and the process of-producin-g butterfly valves in which a valve seat of hard, durable.-corrosion-resistantrnaterial is fused to the valve body by: casting the body. about a preformed seat ring prior to the finished machining thereof. In accordancewith the invention, it 'has been discovered. that .a ring such as an austenitic stainless steel when supported on the mold-core while themolten body material is poured in a con.- ventional manner, will, after cooling, be. contained firmly fused to thebody. By the techniques hereof, the: previous,

problem of ringseparation occasionedby the-.different'shrinkagesbetween the body-'and ring-is reproducibly overcome by employing-critically discoveredageometricparameters of the ringgin relation to its fusing lengthinbond with the body. Hence; there has now been-discoveredfor-thefirst time how a material such as an austenitic stainless steel can be successfully-fusedto a cast iron valve body-'without-the attendantdif flculties that have existed'in prior art devices as noted above to result in a more trouble-freevalve .of greater reliability with reduced "maintenance requirements than heretofore; While specifically usefulzin connection with valves of 'theibutterfly type; the.techniquesin-accordance:with the invention can likewise beemployed-in-themanufacture of other valve=types such as gate valves, plug: valves, ball valves or thelikeinwhich' it is customary to-have a seat engagedlby aclosure member.

It is therefore an object of the invention to provide a valve having a superior seat construction than heretofore.

It is a further object of the invention to provide a novel process for the manufacture of valves whereby a durable, corrosion-resistant seat ring material such as stainless steel having an expansion coefficient greater than a valve body such as cast iron can be fused to the valve body by casting the body about the'seat ring. I

It is a still further object of the invention to provide improved butterfly valves in which the attendant problems heretofore as associated with the seat ring in the valve body are overcome economically and-reliably.

Further" objects, advantages and details will become ap parent from the following description when read in conjunction with'the accompanying drawings, in which:

FIG. I is aplan sectional view of a butterfly valve'with parts partially broken away;

FIG. 2 is a=sectional view taken substantially along the lines 2-2 of FIG. I;

FIG. 3 is an enlargedview of the seat-engaging surfaces encircledin FIG. 2;

FIGS.- 4 and 5 are partial sections illustrating typical seat ringsin their unfinished statein the valve body in accordance herewith; and,

FIG. 6-is a fragmentary view illustrating. typical dimensional parameters before finish machiningof the'seat ring: in relation to the valve body in accordanceherewith.

Referring now to FIG. 1, there isillustrated an embodiment" in the form of a butterfly valve as disclosed in the parent appli cation: hereof. Thervalveincludes a housin'g'corcasinglreferred' to generally by the reference-character C having. an annular wall- 10 to whichiis secured a seat .generallyreferred to as 11 and formed in accordance with the invention as will be described below. At diametrically opposite points with respect to the seat, the wall l0includes aligned cylindrical bores 13 sizedto accommodate Teflon or the likeantifriction bearing sleeves l4 and enlarged at their outer ends to provide counterbores 15; Themain valve cross-shaft is designated l6and is of a noncircular'formationthroughout its length. Carried by the 7 ends" of shaft. 16' within the bores13 are' corrosion-resistant bearingsleeves l7, preferablyof a--corrosion proof material such as-stain'lesssteel. The sleeves each have a noncircular central b'ore corresponding. to the shape of the shaft 16*to receive'and complement the sh'aftth'ereth'rough as to' constitutethe driving connection between the shaft and thebear ing sleeve, The outer-surface of the sleeve is cylindrical and is journaled' within the Teflon sleeve 14;

The vane, new be seen also-in FIG. 2, is-referredtoinits entirety byth'ereference character "V, It includes'acentral cavity l8'through which the shaft'l6 passes and is formed with an internal hub -19. The hubs in -turn are formed with noncircular bores '20 corresponding to the'cross section ofthe shaft 16 received'therein to establish a driving connection between the shaft and vane member.

Atthe outer 'end of each bore "20', there is included a counterbore 21 partially receiving. the bearing sleeve 17 and a static seal22i=likewise fitted therein: Positioned in each'counterbore l5- is an outer'seal '23, which generally comprises rubber' or other suitable elastomeric material, to prevent leakage'offluid from the interior of the housing. At one side,

the seal is held'in-position'by a cover'plate 24- which is secured to the'housingby-means of bolts 9. The'seal 23 on theother" sideisheld in'position in a similar manner by a baseplate '25 associated withthe'valve-operatingmechanism and secured to the housing by bolts 26.

Mounted on the base plate 25-is a housing 27 for the valve operating mechanism generallydesignated as 0. Thislatter housing definesa chamber in'which the'vane' shaft 16" is receivedthrough base plate 25 for'operatively opening. and

closing'the valve via a wrench-engaging member30 all'as' more fully described in the'parent application hereof.

The vane and seat construction with which the invention hereof is' concerned can-be morereadily' understood'witli" reference now'to FIGS. 2 and 3. As thereshown, the-vane V in= cludes a face 32, a generally circular periphery 33 and a notchlike recess 34 at its peripheral corner in which is secured a rubber-or other suitable-type gasket 35. The gasket has an outer rounded or beveled edge 38 which when the vane is in closed position engages seat ring 40 of seat 11 formed in accordance with the invention hereof and shown post-machined in a completed valve with a ground seat surface 45. A clamp means in the form of a ring 4] embeds against the backface of the gasket and a screw 42 passes through aligned openings to secure the gasket to the vane.

While materials such as monel, bronze, or alloy cast iron ASTM A-436 and ductile iron, or steel can be utilized for the ring and body respectively, inthe preferred embodiment the ring 40 is of an austenitic stainless steel of a commercially available grade such as 303, 304 or 316 while the valve body 10 comprises a cast iron of commercial grades such as A 126 or A 48. With these materials, the ring and body have thermal coefficients of expansion respectively of approximately 9.6 X 10 and 6.0 X 106 inches per inch per degree F. with melting points respectively of approximately 2550 F. and 2100 F. This requires casting of the molten iron at a temperature well within the range differential of the melting points and in accordance herewith, conventional casting techniques of a core supported ring are employed, per se forming no part of this invention. However to overcome the tendency to separate between ring and body occasioned by their different shrink rates on cooldown, critical geometrical parameters are selected of the ring. When these parameters are employed, a positive fusing bond results despite and notwithstanding the existing differences in shrinkage by virtue of their respective different thermal expansion coefficients. By means thereof, the formed bond even during cooldown is sufficient to restrain the ring against shrinkage different than the body as to not produce even a partial separation which can be detected anywhere about its cross-sectional parameter.

As can be seen in FIGS. 4 and 5, ring 40 and valve body 10 are shown in their postcooled state before finish machining of the ring. While the cross-sectional configuration or shape of the ring is per se not critical to the invention hereof, it is important and critical to the extent that the line length of bonding contact extending peripherally about the ring at the valve body at least equals or exceeds a predetermined ratio to the cross-sectional area thereof. This relationship, which is defined herein in inch" units, can be expressed in equivalent units by application of an appropriate factor and has been found to be at least a 4.5 inch/inch? In other words, the feature which has been found critical to enable the permanent bonding despite the difference in shrinkage rates between ring and body is the minimum ratio of cross-sectional ring fusing length in contact with the valve body in proportion to the cross-sectional area of the ring determined to be at least 4.5 inch/inch? As will be understood from the sample computations below, various geometries can be employed to achieve this result. Also where because of the valve size, as on the order of 48-inch and above, it becomes economically impractical to develop the required geometry with a single metal or alloyed seat material 40, other integrally attached metals or alloys can optionally be partially substituted. Such a construction is illustrated in FIG. 4in which annular legs 43 of a carbon steel bar are welded to the stainless ring' 40 at 44 to extend radially outward into the body and enable achievement of the required ratio. Carbon steel bars of this type have thermal expansion coefficients of from about the same as cast iron to about 8.6 X l". By this latter means, the fusing length is increased without increasing the cross-sectional area of ring 40. By reference now to the various geometric configurations illustrated in FIGS. 6 A-D, computation of the critical ratio will be further explained. 1

Looking first at FIG. 6A where X=l2 inches; Y;3/8 inch; and Z=l/ 16 inch there results a ratio of 6.3 inch/inch. For the variations shown in FIG. 68 where X=% inch; Y=l7l32 inch; W=% inch; and V,=5/l6 inch there isproduced a ratio of 4.5

inch/inch? In FIG. 6C where A=% inch; B and C=% inch; and D=lll6 inch produces a ratio of 6.1 inch/inch. With the arrangement of FIG. 6D where A=3l4 inch; B=9l 16 inch; C=% inch; D=3/l6 inch; and E=% inch produces a ratio of 4.87 inch/inch. These illustrative dimensional values are of course to be regarded as typical and not as a limitation with respect to the geometry of ring cross section which can be employed since obviously many known geometries can be selected to meet this ratio. It is also to be remembered that these illustrative calculations refer to the relationships as they exist after casting but before finish machining of the ring. Whereas it can be expected that this ratio in the finished product will be varied by reason of further machining of the ring surface to form face 45, the reduction in cross-sectional area is usually proportionately greater than the affected fusing perimeter to increase rather than decrease the ratio in the finished product. While the ratio of 4.5 inch/inch has been established as a critical minimum necessary to effect the proper fusing in accordance herewith, ratios on the order of 6.3 inch/inch and above are to be preferred to allow for eccentricities or other imperfections which may be encountered.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustrative and not in a limiting sense.

We claim:

I. In the method of forming a valve, the improvement including the step of cast fusing a valve body onto a seat-forming material different than said body, said seat-forming material having a coefficient of thermal expansion on at least the seatforming portion thereof greater than said body to be fused into contact therewith in a generally tension relation at the area of contact, the perimeter cross-sectional fusing length of the entire seat material when fused to the cast body being proportional to its entire cross-sectional area in the ratio of at least 4.5 inch/inch. I

2. The improvement according to claim 1 in which the entire seat-forming material has a melting temperature in excess of said body material.

3. The improvement according to claim 2 in which the coefficient of thermal expansion of at least the seat-forming portion of said seat material is at least approximately 50 percent greater than that of the body material.

4. The improvement according to claim 3 in which the seatforming material is comprised of a single metal alloy substantially in its entirety.

5. The improvement according to claim 3 in which the valve body is comprised of cast iron and the seat material in at least the seat-forming portion thereof is comprised of an austenitic stainless steel.

6. The improvement according to claim 5 including the additional step of machining the fused seat material to form a seating surface for a butterfly valve and by which the said ratio is increased as compared to the ratio after casting. 

1. In the method of forming a valve, the improvement including the step of cast fusing a valve body onto a seat-forming material different than said body, said seat-forming material having a coefficienT of thermal expansion on at least the seat-forming portion thereof greater than said body to be fused into contact therewith in a generally tension relation at the area of contact, the perimeter cross-sectional fusing length of the entire seat material when fused to the cast body being proportional to its entire cross-sectional area in the ratio of at least 4.5 inch/inch2.
 2. The improvement according to claim 1 in which the entire seat-forming material has a melting temperature in excess of said body material.
 3. The improvement according to claim 2 in which the coefficient of thermal expansion of at least the seat-forming portion of said seat material is at least approximately 50 percent greater than that of the body material.
 4. The improvement according to claim 3 in which the seat-forming material is comprised of a single metal alloy substantially in its entirety.
 5. The improvement according to claim 3 in which the valve body is comprised of cast iron and the seat material in at least the seat-forming portion thereof is comprised of an austenitic stainless steel.
 6. The improvement according to claim 5 including the additional step of machining the fused seat material to form a seating surface for a butterfly valve and by which the said ratio is increased as compared to the ratio after casting. 